Identify Medical Conditions Necessitating The Drug And Its Potential Impact On The Provision Of Dental Care

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Drug And Its Potential Impact On The Dental Care When a patient presents with a lengthy

medication list, a primary concern is whether or not there are medications on the list that may be required in the event of an emergency.  The patient’s drugs should be categorized to identify immediate safety considerations

Does the patient require nitroglycerin for anginaor an inhaler for dyspnea?  If so, these drugs should be available during the dental appointment.

Important consideration  Secondly, do any of the drugs on the

list have the potential to complicate dental treatment?  For example, is the patient taking the anti-coagulant Warfarin?  If so, has the patient’s physician been alerted to the pending dental treatment and have all the necessary lab tests been run and the results available?

Has the patient taken their dose of insulin but not eaten, placing them at risk for hypoglycemia?

Important consideration  Third, could any of the medications

compromise our treatment outcomes?  For example, is the healing time or risk of infection increased because the patient is on immunosuppressants such as Prednisone or chemotherapeutics such as Vincristine or Methotrexate?

Potential drug related oral health/management complications.

Drug GroupsExample Drugs

Management Problems

AnticoagulantsAspirin,

Warfarin*Excessive bleeding

Immunosuppressants

Corticosteroids*

Immunosuppressants for

organ transplants*

 Increase risk of bacterial and fungal infection, poor stress

response 

Chemotherapeutic agents Vincristine

 Delayed healing, mucositis, fungal infections 

Drug GroupsExample DrugsManagement Problems

Sedative hypnotics*, narcotics,

barbituratesTylenol, Valium,

Demerol Respiratory suppression, fall

risk 

HypoglycemicsInsulin*,

sulfonylureasHypoglycemia

Bisphosphonate bone stabilizers

Pamidronate (Aredia)

Alendronate (Fosmax)

Delayed bone healing,bone necrosis

Potential drug related oral health/management complications.

Natural products that may alter dental

management

Many natural products can have a physiologic impact that requires altered dental management, so the clinician should be sure to inquire if the patient is taking any natural products

Natural products that may alter dental

management CompoundPossible Dentally Relevant

Problem

FeverfewGarlic

, GingerGinko Biloba

BilberryDong Quai

St. John’s Wort

May increase bleeding

EchinaceaSt. John’s Wort

These herbs inhibit liver enzymes so they may

potentiate the liver enzyme (cytochrome P450) inhibiting the effect of erythromycin and

ketokonazole.

Natural products that may alter dental

management CompoundPossible Dentally Relevant

Problem

Ephedra (Ma-Huang) Bitter orange

May increase blood pressure and heart rate due to anxiety

or if epinephrine/vasoconstrictor

used.

Kava-KavaHepatotoxicity, especially in those taking other

medications metabolized in the liver. Sedative effects.

ValerianMay potentiate the effects of sedative Hypnotics and anti-

anxiety drugs

Create A System For Prescribing

Reviewing with the patient the indications for all medications on the list allows the dentist the opportunity to clarify the health history and provides important information about the patient and any potential risks or management issues to be considered when treating the patient.

Create A System For Prescribing  In some cases the patient will not be able to

effectively communicate their health issues, in which case their medication list may be the dental clinician’s only immediate resource for identifying medical problems which are so severe they require pharmacologic intervention.

For instance, a patient may not report they have hypertension, but their medication list may include Furosemide, a diuretic.  Both the hypertension and the diuretic can have implications on the provision of dental care as well as direct and indirect effects on the patient’s oral health.

Create A System For Prescribing

After carefully reviewing the existing medications to assess the patient’s systemic condition and considering the potential effects of the medication on oral health

the next consideration relates to drugs administered or prescribed for the patient by the dentist

Create A System For Prescribing The first consideration is “are there any

absolute contraindications to the medication that will be prescribed,” such as a drug allergy?  

Does the drug have the potential to exacerbate any of the patient’s medical conditions (i.e., drug-physiology interaction), such as NSAIDs increasing the risk of gastrointestinal bleeding in a patient with gastric ulcers? 

Create A System For Prescribing Does the drug have the potential to

interact with any of the over-the-counter, herbal supplements or medications reportedly taken by the patient such as erythromycin, inhibiting liver enzymes and decreasing the metabolism of the anti-coagulant Coumadin?

 Patients taking are at high risk of developing drug-drug interactions. some of these drugs are highly titrated and a small change in their blood levels can have a large physiological impact.

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Four drugs commonly used in dentistry, inhibit cytochrome P450 enzymes

1. Erythromycin2. Clarithromycin3. Metronidazole4. ketoconazole,.  

Create A System For Prescribing The P450 enzymes enzymes are

responsible for metabolizing many drugs.  Their inhibition of drugs used in dentistry can significantly decrease the rate of drug metabolism.  

Erythromycin and ketoconazole have the greatest potential to cause such inhibition.  So, to avoid the risk of such drug-drug interactions, do not use these drugs in patients already taking other drugs.

Create A System For Prescribing It may be useful to review reference books or

websites at this point to see if there are any contraindications or precautions to taking a particular drug with a coexisting medical condition or to taking the medication with a currently prescribed medication.

Some resources are very convenient such as Lexicomp’s electronic drug interaction software that allows you to enter the drug in question and cross check it for interactions. Importantly, pharmacists can also be consulted to clarify seemingly ambiguous information

Create A System For Prescribing In order to avoid drug toxicity the

prescriber must be aware of how the drug will be eliminated when selecting a drug or determining dosages.  

This is especially important if the patient has known renal or hepatic disease, since these are the most common routes of elimination.  

If they are available, some laboratory values may serve as guidelines for prescribing drugs eliminated by the kidney or liver

Guidelines for compromised renal or hepatic function

Potential impairment

Examples of dental drugs eliminated

Lab testRangeMargin of safety for dental prescribing

Renal Amoxicillin Cephalosporin

PenicillinTetracycline

GFR (Creatinin

e Clearanc

e)

<10 ml/min 10-50 ml/min 

>50 ml/min

One dose q 24 hrs One dose q 8-12 hours 

One dose q 8 hours 

Hepatic Acetaminophen

CodeineDiazepam

ErythromycinIbuprofen

KetoconazoleLidocaine LorazepamPrednisone

AST, ALT, liver transamin

ases

30-40 u/lIf greater than 4 times normal, do not use

drugs that are toxic to or metabolized by the

liver

Dealing with Patients of advanced age Patients of advanced age may be at

increased risk of suffering the respiratory depressive effects of some medications such as benzodiazepines and opioids.

They may be less able to compensate quickly for medications that alter cardiovascular function, such as epinephrine

they may have an atypical adverse drug response such as altered mental status.

Dealing with Patients of advanced age It should be noted few adverse drug

events have been clearly attributed to the changes that occur in the processes of absorption, distribution, and elimination as a result of normal aging.

Risks associated with altered drug metabolism and elimination are almost always due to the presence of a known systemic disease affecting cardiac, kidney, or liver function

Dealing with Patients of advanced age

Some drugs present an increased risk of toxicity in older individuals, even without a drug interaction.  In addition to screening for potential adverse drug interactions knowledge of maximum doses of the drugs to be prescribed for a dental purpose is critical

Dealing with Patients of advanced age  A decrease in dosage for aged individuals

may be recommended for some medications commonly used in dentistry  Due to normal physiologic changes in elimination associated with aging and altered distribution as a result of decreased body mass, dosage of these drugs should be reduced by 50% or to the lowest therapeutic dose for individuals under 100 pounds and patients over 85 years old

Dealing with Patients of advanced age

Drug classDrug

AntibioticAmoxicillinCephalosporinTetracycline

AntifungalFluconazole

Renal Elimination

Dealing with Patients of advanced age

Hepatic Elimination 

Drug classDrug

Pain relieverIbuprofen

AntibioticErythromycin

Local anestheticLidocaine

Sedative/anxiolyticDiazepam Lorazepam

Dental Toxicology

HEAVY METALS AND ANTIDOTES

HEAVY METALS AND ANTIDOTES

Lead

Absorption Skin: alkyl lead compounds, because

of lipid solubility (methyl and tetraethyl lead)

Inhalation: up to 90% depending upon particle size

GI: adults 5 to 10%, children 40%

Lead

Distribution Initially carried in red cells and

distributed to soft tissues (kidney and liver); redistributed to bone, teeth and hair mostly as a phosphate salt.

Half life in blood 30-60 days, bone 20-30 years

Lead

Rates of absorption and distribution are greatly influenced by dietary intake and body stores of phosphate, calcium and iron relative to lead high PO4, Pb storage in bone high Vitamin D, Pb storage in soft tissue low PO4, Pb sequestered in soft tissue high Ca++, Pb sequestered in soft

tissue

Lead

Mechanisms of toxicity Inhibition of heme biosynthesis. Heme

is the essential structural component of hemoglobin, myoglobin and cytochromes.

Binds to sulfhydryl groups (-SH groups) of proteins

Lead

Mechanisms of toxicity

Lead Diagnosis

(1) History of exposure (2) Whole blood lead level

Children: >25μg/dl treatments Adults: >50 μg/dl candidates for treatment; > 80

μg/dl & symptomatic, treatment initiated, >120 μg/dl encephalopathy

(3) Protoporphyrin levels in erythrocytes are usually elevated with lead levels > 40 μg/dl

(4) Urinary lead excretion >80 μg/dl

Lead

Symptoms (1)Acute - nausea, vomiting, thirst,

diarrhea/constipation,hemoglobinuria, hypovolemic shock

(2)Chronic - GI: lead colic (nausea, vomiting, abdominal

pain) CNS: lead encephalopathy

(headache,irritation, insomnia, CNS edema)

Lead

Treatment (1) Remove from exposure (2) chelating agents

CaNa2EDTA 2,3-dimercaptopropanol (Dimercaprol,

BAL) 2,3-dimercaptosuccinic acid (Succimer) D-penicillamine

Mercury (Hg) Absorption GI:

inorganic salts are variably absorbed (10%) but may be converted to organic mercury (methyl and ethyl in the gut by bacteria)

organic compounds are well absorbed >90%

Inhalation: elemental Hg completely absorbed

Mercury (Hg) Distribution depends upon sources of

exposure Elemental Hg (vapor) crosses membranes well

and rapidly moves from the lung to the CNS. Organic salts (lipid soluble) are evenly

distributed, intestinal (intracellular)-fecal elimination.

Inorganic salts concentrate in blood, plasma and kidney (renal elimination).

Half life is 60 to 70 days.

Mercury (Hg)

Mechanisms of toxicity destruction of mucosal membranes necrosis of proximal tubular

epithelium inhibition of sulfhydryl (-SH) group

containing enzymes

Mercury (Hg)

Diagnosis History of exposure Blood mercury

Mercury (Hg) Symptoms Acute

(inorganic salts) degradation of mucosa-GI pain, vomiting, diuresis, anemia, hypovolemic shock, renal toxicity.

(organic) CNS involvement- vision, depression,, insomnia, fatigue, diuresis.

Chronic: CNS symptoms similar to acute organic poisoning

Mercury (Hg) Treatment

Remove from exposure Hg and Hg salts > 4 μg/dl : 2,3-

dimercaptopropanol (BAL),penicillamine, most effective is N-acetyl-penicillamine

(3) Methyl Hg- supportive treatment (nonabsorbable thiol resins can be given orally to reduce methyl Hg level in the gut).